The main difference between ORD/ORU and the approaches at [1]} and [2]} is that ORD/ORU produce an output of controllable size, respecting the OSS property, as seen in Table  REF. Also, F-skylines and UTK utilize a fixed polytope region given in advance to establish dominance, whereas the ORD/ORU dominance region is effectively a hyper-sphere and usually not given in advance. Therefore, as established in [3]}, ORD/ORU are hardly comparable, in terms of output data, to the other two techniques. However, focusing on performance only, ORD/ORU algorithms are much more efficient than F-skylines and UTK. ORD, in particular, is 2 to 4 orders of magnitude faster than F-skylines while ORU is 12 to 134 (or even more in some cases) faster than JAA, the best algorithm for fixed region approaches, employed by UTK.
